Amazon's Gold Box deal of the day is the Seagate ST31000524AS 1 TB 7200 rpm SATA hard-drive for $47 with free shipping. Newegg has this same drive for $60.
I've about decided to stick to 2.0 to 2.2 TB drives from Samsung or Western Digital, but if a 1 TB 7200 rpm drive suits your needs, this is a good price.
$47 per TB = 4.7¢ per GB.
Amazon also had the OCZ Solid 3 120GB SSD on sale for $200 from 7 to 9 AM today. $1667 per TB = 166.7¢ per GB. That's more than 35 times as expensive as the mechanical hard-drive in this deal.